This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. In the model eukaryote Saccharomyces cerevisiae, cell cycle events are coordinated with constitutive functions like energy generation and duplication of protein mass. The latter processes are stimulated by the Rap1p/Gcr1p/Gcr2p complex, which activates transcription of the genes required for rapid growth;this includes glycolytic and ribosomal protein genes, which are among the most heavily transcribed in the cell. In vivo 32P labeling has shown that Rap1p, Gcr1p, and Gcr2p are all phosphoproteins. Mapping the exact sites of phosphorylation in these proteins would represent an important advance in our understanding of the signaling cascade(s) that regulates the Rap1 activation complex. Mass spectrometry (LC-MS/MS) will be used to analyze phosphorylation sites in these factors.